Field of the invention
The present invention relates to a method of evaluating metal contamination in a boron-doped p-type silicon wafer.
The present invention further relates to an evaluation device employed in the above evaluation method, and to a method of manufacturing one or more boron-doped p-type silicon wafers comprising quality control by means of the above evaluation method.
Discussion of the Background
Fe is a typical example of contaminant metal in silicon wafers. Various methods, including the microwave photoconductive decay method (μ-PCD method) and surface photovoltage method (SPV method), have been proposed and put to practical use as methods of evaluating Fe contamination.
Among metals other than Fe, for example, Co tends to diffuse from the interior to the surface of a silicon wafer during cooling due to a rapid diffusion rate. The diffused Co forms precipitates on the surface of the silicon wafer, negatively impacting device characteristics. Accordingly, the quantification of Co by the SPV method is proposed in “Cobalt Contamination in Silicon”, M. L. Polignano et al., Solid State Phenomena Vols. 108-109 (December 2005) pp. 571-576, which is expressly incorporated herein by reference in its entirety, for example. Further, the SPV method is proposed in “Influence of Cobalt Contamination in the Measurement of Diffusion Length of P-type CZ Silicon Wafers” Nicolas Pic et al. Analytical and Diagnostic Techniques for Semiconductor Materials, Devices and Processes symposium and Proceedings sponsored by: The Electrochemical Society ECS PV 2003-03 p505, which is expressly incorporated herein by reference in its entirety, for the detection of Co in silicon wafers.